Recently, researches about polymer electrolytes have been spotlighted owing to their potential applications in polymer batteries, fuel cells and solar cells. To our knowledge, no report has been published on polymer electrolytes by pi-complexation between transition metal ion and olefinic ligand of a polymer matrix although several have been reported by the coordination between metal ion and nonbonding electrons of oxygen. nitrogen, etc. In this Communication, we report that polymer electrolytes consisting of silver salt and polymer containing C=C bond are developed and especially applied to the facilitated olefin transport membranes for the separation of olefin/paraffin mixtures. (C) 2004 Elsevier B.V. All rights reserved.